Solubility of solids in supercritical fluids was studied by chemical association reaction method in this work, where both cases of with and without cosolvent were considered. Based on the thermodynamic and association reaction equilibrium theories, a model for the solubility of solids in supercritical fluids under association reactions was developed, which reduces to normal solubility calculation model when there are no cosolvent and association reactions. The model was tested with the experimental data collected from the literature, and the results show that it is more accurate than other models.